Electrometer

ABSTRACT

An electrometer includes a sensing module and a control module. The sensing module includes a plurality of electrostatic sensing elements and a plurality of second electrodes. The plurality of electrostatic sensing elements are single walled carbon nanotubes or few-walled carbon nanotubes. The plurality of electrostatic sensing elements and the plurality of second electrodes are alternately arranged in a series connection. The control module is coupled to the two ends of the series connection and configured to measure a resistance variation ΔR of the series connection and convert the resistance variation ΔR into a static electricity potential.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims all benefits accruing under 35 U.S.C. §119 fromChina Patent Application No. 201410850029.9, filed on Dec. 31, 2014, inthe China Intellectual Property Office. This application is related tocommonly-assigned application entitled, “ELECTROMETER”, concurrentlyfiled (Atty. Docket No. US56363); “ELECTROSTATIC DISTRIBUTION MEASURINGINSTRUMENT”, concurrently filed (Atty. Docket No. US56361). Disclosuresof the above-identified applications are incorporated herein byreference.

FIELD

The present application relates to an electrometer.

BACKGROUND

Electrometer is an electrical instrument for measuring the staticelectricity potential. The electrometer can be divided into twocategories: contact electrometer and non-contact electrometer. Comparedwith the contact electrometer, the non-contact electrometer based on theprinciple of electrostatic induction is less influenced by inputcapacitance and input resistance. The measurement accuracy of anon-contact electrometer is better than a contact electrometer. However,the non-contact electrometer can not be used to monitor the staticelectricity potential for the test value of the non-contact electrometerwill decay exponentially with time.

What is needed, therefore, is to provide an electrometer to monitor thestatic electricity potential.

BRIEF DESCRIPTION OF THE DRAWINGS

Implementations of the present technology will now be described, by wayof example only, with reference to the attached figures, wherein:

FIG. 1 is a schematic view of one embodiment of an electrometer.

FIG. 2 is an electron density of state distribution curve of carbonnanotube.

FIG. 3 is an electron density of state distribution curve of carbonnanotube under normal temperature measured by Scanning tunnelingspectroscopy (STS).

FIG. 4 is a schematic view of one embodiment of an electrometer.

FIG. 5 is a schematic view of one embodiment of an electrometer.

FIG. 6 is a schematic view of a sensing module in the embodiment shownin FIG. 5.

FIG. 7 is a schematic view of one embodiment of an electrostaticdistribution measuring instrument.

DETAILED DESCRIPTION

It will be appreciated that for simplicity and clarity of illustration,where appropriate, reference numerals have been repeated among thedifferent figures to indicate corresponding or analogous elements. Inaddition, numerous specific details are set forth in order to provide athorough understanding of the embodiments described herein. However, itwill be understood by those of ordinary skill in the art that theembodiments described herein can be practiced without these specificdetails. In other instances, methods, procedures and components have notbeen described in detail so as not to obscure the related relevantfeature being described. The drawings are not necessarily to scale andthe proportions of certain parts may be exaggerated to better illustratedetails and features. The description is not to be considered aslimiting the scope of the embodiments described herein.

Several definitions that apply throughout this disclosure will now bepresented.

The term “coupled” is defined as connected, whether directly orindirectly through intervening components, and is not necessarilylimited to physical connections. The connection can be such that theobjects are permanently connected or releasably connected. The term“substantially” is defined to be essentially conforming to theparticular dimension, shape or other word that substantially modifies,such that the component need not be exact. For example, substantiallycylindrical means that the object resembles a cylinder, but can have oneor more deviations from a true cylinder. The term “comprising” means“including, but not necessarily limited to”; it specifically indicatesopen-ended inclusion or membership in a so-described combination, group,series and the like.

The disclosure is illustrated by way of example and not by way oflimitation in the figures of the accompanying drawings in which likereferences indicate similar elements. It should be noted that referencesto “an” or “one” embodiment in this disclosure are not necessarily tothe same embodiment, and such references mean at least one.

Referring to FIG. 1, an electrometer 100 of one embodiment includes asensing module 10 and a control module 50 electrically connected to thesensing module 10.

The sensing module 10 includes an electrostatic sensing element 12 andtwo electrodes 14 electrically connected to the electrostatic sensingelement 12. The electrostatic sensing element 12 includes two oppositeends. The two electrodes 14 are separately located on the two oppositeends.

The electrostatic sensing element 12 can be one-dimensionalsemiconducting linear structure in nanoscale with single crystalstructure. A diameter of the one-dimensional semiconducting linearstructure in nanoscale is less than 100 nanometers. When a measuredobject with electrostatic charge is near but does not touch theelectrostatic sensing element 12, the resistance of the electrostaticsensing element 12 can be changed. The resistance change can be obtainedby detecting current change of the electrostatic sensing element 12. Themeasured object with any static charge can be regarded as the measuredobject with electrostatic charge in this disclosure. In someembodiments, a user's finger(s) are as an example of the measured objectwith electrostatic charge.

The one-dimensional semiconducting linear structure in nanoscale can bea semiconducting linear structure with larger length diameter ratio. Thelength diameter ratio of the one-dimensional semiconducting linearstructure is greater than 1000:1.

The electrostatic sensing element 12 can be semiconducting graphenestrips with a width of less than 10 nanometers, a thickness of less than5 nanometers, and a length of greater than 1 centimeter. Theelectrostatic sensing element 12 can be one semiconducting siliconnanowire with a diameter of less than or equal to 5 nanometers, and alength of greater than 1 centimeter. The electrostatic sensing element12 can be one ultra long single walled carbon nanotube or few-walledcarbon nanotube. The few-walled carbon nanotube is a carbon nanotubewith wall of from about two layers to about six layers. In oneembodiment, the few-walled carbon nanotube has two or three layers wall.

When a measured object with electrostatic charge is near but does nottouch the one-dimensional semiconducting linear structure in nanoscale,the resistance of the one-dimensional semiconducting linear structure innanoscale can be changed. The measured object can be recognized by adevice because the resistance of the one-dimensional semiconductinglinear structure in nanoscale is changed. An electric field generated bystatic electricity of the measured object can easily affect Fermisurface moving of the one-dimensional semiconducting linear structure innanoscale. Electric field outside the one-dimensional semiconductinglinear structure in nanoscale would affect Fermi surface movement of theone-dimensional semiconducting linear structure in nanoscale.Conductivity of the one-dimensional semiconducting linear structure innanoscale significantly changes with the Fermi surface movement of theone-dimensional semiconducting linear structure in nanoscale.

The one-dimensional semiconducting linear structure in nanoscale hasexcellent response to the electric field of the send object for belowreasons. Almost the one-dimensional semiconducting linear structure innanoscale can not constitute an electric field shielding, and it can becompletely regulated by external electric field. While electric fieldapplied on a three-dimensional conductive material can hardly affectinternal of the three-dimensional conductive material, because of thethree-dimensional conductive material having a strong surface shielding.Due to the quantum confinement effect, the electron density of states(DOS) of one-dimensional material would have many singularities. Whilethe Fermi surface is moving near the singularity, the electronic densityof states will dramatically changes. The dramatic changes of theelectronic density of states would lead to the conductivity of theone-dimensional semiconducting linear structure in nanoscale significantchanges.

Therefore, electrostatic can modulate the Fermi surface moving in thevicinity of the singularity in the one-dimensional semiconducting linearstructure in nanoscale, to get a significant change in the electricalconductivity of the semiconducting linear structure in nanoscale.Therefore, the measured object with electrostatic charge can berecognized by the one-dimensional semiconducting linear structure innanoscale when the measured object is near but does not touch thesemiconducting linear structure in nanoscale. In order to realize thissensing static function, the distance between the Fermi surface and thesingularity of the one-dimensional semiconducting linear structure innanoscale should be within a specific range.

As shown in FIG. 2, the electron density of states distribution curve ofthe carbon nanotube have a lot of singularities. The electron density ofstates of the carbon nanotube takes great value at the point of thesingularity. Distribution of singularities is relatively symmetrical to0 eV place. In an ideal state without making any doping, the Fermi levellocates on 0 eV place. The above properties are all one-dimensionalsemiconducting linear structure common characteristics. As previouslymentioned, a sensitive response to the electrostatic requires Fermisurface moving in the vicinity of the singularity of one-dimensionalsemiconducting linear structure. So that there is a need to make theFermi level to raise or decrease to the neighborhood singularity nearestto 0 eV. Referring to FIG. 3, in practice, due to the thermalexcitation, surface adsorption and interaction with the surroundingenvironment, the singularities of one-dimensional semiconducting linearstructure will be broadened into a half-height peak with a width L. Thepeaks are always to be buried because the overlap of the peaks. But, therising edge of peak singularity nearest 0 eV is always present. To makethe one-dimensional semiconducting linear structure having sensitiveresponse to electrostatic, the Fermi surface needs to be fixed at aplace with a distance to the singularity less than L/2. In practicalapplications, to obtain sensitive response to electrostatic, throughnatural doping or manual doping, to make the energy distance between theFermi surface and the singularity of the one-dimensional semiconductinglinear structure within a range of 30 meV˜300 meV.

Carbon nanotubes prepared sample exposed to air, since the formation ofoxygen adsorbed p-type doped, the energy distance from the Fermi surfaceto singular points in the state density falls within 30˜300 meV,preferably 60 to fall within 100 meV. Therefore, thereby manual preparednatural carbon nanotubes have electrostatic sensitive electrostaticresponse. Graphene strips, semiconducting nanowires (e.g. siliconnanowires) can adsorb oxygen to form a p-type doping. A doping can alsobe used to adjust energy distance between the Fermi surface and thesingular point in the state density within a distance of 30˜300 meV.

When the measured object with electrostatic charge nears theone-dimensional material semiconducting linear structure in nanoscale,the Fermi level of the one-dimensional semiconducting linear structurein nanoscale would be modulated, the corresponding density of stateswill change, and the conductivity will change consequently. Therefore,when considering the sensitivity of the process, it is needed to focuson two things: first, modulation efficiency of the measured object tothe Fermi level of the one-dimensional semiconducting linear structurein nanoscale; second, the change rate of the density of states with theFermi level moving of the one-dimensional semiconducting linearstructure in nanoscale.

With respect to the first point, this is strongly influenced by thesubstrate material, the surface adsorption and other environmentalfactors. It is impossible to quantitatively determine the modulationefficiency of the measured object to the Fermi level of theone-dimensional semiconducting linear structure in nanoscaletheoretically. The modulation efficiency of the measured object to theFermi level of the one-dimensional semiconducting linear structure canonly be obtained from experimental measurements. Silica, for example, asample of the silica substrate, the modulation efficiency is measured as4×10⁻⁵. The second point is a requirement about the one-dimensionalsemiconducting linear structure in nanoscale, which requires theabsolute value of (dσ/dE_(F)/(σ/E_(F)) greater than 10⁻¹, or greaterthan 10⁻³ (σ is the conductivity of the one-dimensional semiconductinglinear structure in nanoscale, E_(F) is the Fermi surface location ofthe one-dimensional semiconducting linear structure in nanoscale). Inthis condition, when the measured objection is close to theone-dimensional semiconducting linear structure in nanoscale, theconductivity change is not less than 10% in favor to signal detection.

When using carbon nanotubes with the diameter distribution of 2-3 nm(carbon nanotubes are located on a silica substrate), the conductivityof the carbon nanotubes reduce by half (dσ/σ˜½), when a measured objectwith electrostatic charge 1000V is close to the carbon nanotubes at aplace 0.5 centimeter far from the carbon nanotubes. The modulationefficiency is measured as 4×10⁻⁵, dE_(F)˜40 meV. The E_(F) of the carbonnanotubes is E_(F)˜150 meV. Thus, the absolute value of(dσ/dE_(F)/(σ/E_(F)) of the carbon nanotube is about 2. The graphenestrips, the semi-conductive nano-wires can satisfy the requirement of(dσ/dE_(F)/(σ/E_(F)) is greater than 10⁻¹, or greater than 10⁻³. If itis just to achieve a qualitative sense the presence or absence of themeasured object with static electricity, (dσ/dE_(F))/(σ/E_(F)) ofone-dimensional semiconducting linear structure in nanoscale is greaterthan 10⁻³. If it is to quantify the amount of sensing electrostatic orsense the position of the measured object with static electricity,(dσ/dE_(F))/(σ/E_(F)) of one-dimensional semiconducting linear structurein nanoscale is greater than 10¹.

One single walled carbon nanotube or few-walled carbon nanotube isquasi-one-dimensional structure. The smaller the diameter of thequasi-one-dimensional structure is, the density of state (DOS) of thequasi-one-dimensional structure is greater. The greater the DOS of thequasi-one-dimensional structure is, the shielding effect of thequasi-one-dimensional structure is smaller. And accordingly, the smallerthe shielding effect of the quasi-one-dimensional structure is, thesensibility of sensing static electricity of the quasi-one-dimensionalstructure is greater. Therefore, the smaller the diameter of the singlewalled carbon nanotube or few-walled carbon nanotube is, the sensibilityof sensing position coordinate of the measured object is greater.

The diameter of the single walled carbon nanotube or few-walled carbonnanotube can be less than about 5 nanometers. In one embodiment, thediameter of the single walled carbon nanotube or few-walled carbonnanotube is in a range from about 2 nanometers to about 5 nanometers. Inone embodiment, the diameter of the single walled carbon nanotube orfew-walled carbon nanotube is about 2 nanometers. The length of thesingle walled carbon nanotube or few-walled carbon nanotube is notlimited. The longer the length of the electrostatic sensing element 12is, the measurement space of the electrostatic sensing element 12 isgreater, the measurement accuracy of the electrostatic sensing element12 is worse. In one embodiment, the length of the single walled carbonnanotube or few-walled carbon nanotube is less than or equal to 5micrometers.

The sensing module 10 can further includes a substrate 16. The substrate16 is made of insulating materials. The insulating materials can berigid materials such as glass, quartz, diamond or any other suitablematerial. The insulating materials can also be flexible materials suchas plastic, resin or any other suitable material. A shape and size ofthe substrate 16 can be selected according to need. The substrate 16 cansupport and protect the electrostatic sensing element 12. In oneembodiment, the substrate 16 is a hollowed column. The electrostaticsensing element 12 and the electrode 14 can be completely or partiallycovered by the substrate 16. The length of the hollowed column isgreater than the electrostatic sensing element 12, the sidewallthickness of the hollowed column is about 1 micrometers. Theelectrostatic sensing element 12 and the two electrodes 14 are disposedwithin the cavity of the hollowed column. Alternatively, theelectrostatic sensing element 12 and electrode 14 can be located on thesurface of the substrate 16. It is also to be understood that it doesnot affect the function of the electrometer 100 without the substrate16, the substrate 16 is optional.

The two electrodes 14 can be formed by conductive material, such as Au,Ag, Cu, Pd, or indium tin oxide (ITO). The shape of the two electrodes14 is not limited. In one embodiment, the electrostatic sensing element12 and the two electrodes 14 are located on the surface of the substrate16, the two electrodes 14 is made of Ag, and located on the two oppositeends of the electrostatic sensing element 12 respectively. It is also tobe understood that the electrostatic sensing element 12 can be directlyconnected to the measuring unit 52 without the two electrodes 14, thetwo electrodes 14 is optional.

The control module 50 includes a measuring unit 52 and a processing unit54. The measuring unit 52 is used to measure the resistance variation ΔRof the electrostatic sensing element 12 and transmit the resistancevariation ΔR to the processing unit 54. The processing unit 54 is usedto convert the resistance variation ΔR into the static electricitypotential. Data can transmit between the measuring unit 52 and theprocessing unit 54. Data transmission between the processing unit 54 andthe measuring unit 52 may be wireless transmission or wiredtransmission. In wireless transmission, the distance between theprocessing unit 54 and the measuring unit 52 can be very long.

The measuring unit 52 is electrically connected to the two opposite endsof the electrostatic sensing element 12. The measuring unit 52 can bedirectly connected to the electrostatic sensing element 12. Themeasuring unit 52 can also be connected to the electrostatic sensingelement 12 via the two electrodes 14. In one embodiment, the measuringunit 52 is electrically connected to the two electrodes 14 via twosupporting bars 56 which can support the electrostatic sensing element12. The two supporting bars 56 can be made of a metal that has goodelectrical conductivity. In one embodiment, the two supporting bars 56are made of copper, the length of the two supporting bars 56 is about 20cm and the diameter is about 0.5 cm. It is understood that the twosupporting bar 56 can be replaced by other conductive connector.

The measuring unit 52 is used to measure the resistance variation ΔR ofthe electrostatic sensing element 12 and transmit the resistancevariation ΔR to the processing unit 54. The resistance variation ΔR canbe calculated using the following equation: ΔR=R′−R, wherein R is theinitial resistance of the electrostatic sensing element 12 without themeasured object, and R′ is the resistance of the electrostatic sensingelement 12 when the measured object with electrostatic charge is nearbut does not touch the electrostatic sensing element 12. The method toobtain the resistance R′ or R is not limited, such as voltammetry orwheatstone bridge. In one embodiment, the resistance is obtained by thevoltammetry method, which comprises the following steps: applying avoltage U to the electrostatic sensing element 12 and detecting thecurrent of the electrostatic sensing element 12; recording the currentof the electrostatic sensing element 12 without the measured object, andrecording the current of the electrostatic sensing element 12 when themeasured object with electrostatic charge is near but dose not touch theelectrostatic sensing element 12. The resistance variation ΔR iscalculated using the following equation: ΔR=U/I−U/I′, wherein I is thecurrent of the electrostatic sensing element 12 without the measuredobject, I′ is the current of the electrostatic sensing element 12 whenthe measured object with electrostatic charge is near but dose not touchthe electrostatic sensing element 12. The distance between theelectrostatic sensing element 12 and the measured object can range fromabout 1 mm to about 50 mm. In one embodiment, the distance between theelectrostatic sensing element 12 and the measured object is 25 mm. Themeasurement range of the electrometer 100 can be changed by adjustmentof the distance between the electrostatic sensing element 12 and themeasured object.

The processing unit 54 is used to convert the resistance variation ΔRinto the static electricity potential. The resistance variation ΔRmeasured by the measuring unit 52 is send to the processing unit 54, andconverted into the static electricity potential by the processing unit54.

In one embodiment, the processing unit 54 includes a converting unit(not shown) and an output unit (not shown). The converting unit is usedto convert the resistance variation ΔR into the static electricitypotential. The output unit is used to output the results of theconverting unit. The output results may be a value, light, sound orother signals.

The electrometer 100 may further include an alarm unit (not shown) whichmonitors the static electricity potential. When the static electricitypotential reaches a preset threshold, the alarm unit sends out alarmsignals.

Referring to FIG. 4, an electrometer 200 of one embodiment includes asensing module 20 and a control module 60 electrically connected to thesensing module 10.

The sensing module 20 includes an electrostatic sensing element 12, afirst electrode 24 a, a second electrode 24 b, a third electrode 24 cand a fourth electrode 24 d. The first electrode 24 a, the secondelectrode 24 b, the third electrode 24 c and the fourth electrode 24 dare sequentially located along a longitudinal direction of theelectrostatic sensing element 12. The first electrode 24 a and thefourth electrode 24 d are located on the two opposite ends of theelectrostatic sensing element 12. The second electrode 24 b and thethird electrode 24 c are located on the middle part of the electrostaticsensing element 12. When the measured object with electrostatic chargeis near, but does not touch, the electrostatic sensing element 12, theresistance of the electrostatic sensing element 12 can be changed.

The control module 60 is electrically connected to the electrostaticsensing element 12 via the four electrodes 14. The control module 60includes a measuring unit 62 and the processing unit 54. The measuringunit 62 is used to measure the resistance variation ΔR of theelectrostatic sensing element 12 by Four-terminal sensing method. TheFour-terminal sensing method comprises the following steps: applying acurrent I to the electrostatic sensing element 12 via the firstelectrode 24 a and the fourth electrode 24 d, and detecting the voltagebetween the second electrode 24 b and the third electrode 24 c. Theresistance variation ΔR can be calculated using the following equation:ΔR=U/I−U′/I, wherein U is the voltage between the second electrode 24 band the third electrode 24 c without the measured object, U′ is thevoltage between the second electrode 24 b and the third electrode 24 cwhen the measured object with electrostatic charge is near but dose nottouch the electrostatic sensing element 12. The resistance variation ΔRmeasured by the measuring unit 62 is send to the processing unit 54 andconverted into the static electricity potential.

The electrometer 200 in the embodiment shown in FIG. 4 is similar to theelectrometer 100 in the embodiment shown in FIG. 1, except that theelectrometer 200 measures the resistance variation ΔR by Four-terminalsensing method which can improve the measurement accuracy by reducingthe influences of lead resistance and electrode resistance.

Referring to FIG. 5, an electrometer 300 of one embodiment includes asensing module 30 and a control module 50 electrically connected to thesensing module 30.

The sensing module 30 includes a plurality of electrostatic sensingelements 12, two first electrodes 34A, and a plurality of secondelectrodes 34B. The number of the sensing elements 12 is N and thenumber of the second electrodes 34B is N−1. N is an integer greaterthan 1. The N electrostatic sensing elements 12 are spaced apart fromeach other. The N electrostatic sensing elements 12 are connected inseries via the N−1 second electrodes 34B. The N electrostatic sensingelements 12 and the N−1 second electrodes 34B are alternately arrangedin a series connection. The series connection has two ends. Each end ofthe series connection is electrically connected to a first electrode34A. When the measured object with electrostatic charge is near but doesnot touch the series connection, the resistance of the series connectioncan be changed.

The control module 50 includes a measuring unit 52 and a processing unit54. The measuring unit 52 is electrically connected to the two ends ofthe series connection. The measuring unit 52 is used to measure theresistance variation ΔR of the series connection and transmit theresistance variation ΔR to the processing unit 54.

The electrometer 300 in the embodiment shown in FIG. 5 is similar to theelectrometer 100 in the embodiment shown in FIG. 1, except that theelectrometer 300 includes N electrostatic sensing elements 12. The Nelectrostatic sensing elements 12 are insulated from each other. Thearrangement of the N electrostatic sensing elements 12 is not limited.In one embodiment, the N electrostatic sensing elements 12 aresubstantially parallel to each other. The distance between two adjacentelectrostatic sensing elements 12 can be in a range from about 2 mm toabout 2 cm.

In one embodiment, the sensing module 30 includes seven electrostaticsensing elements 12, two first electrodes 34A, and six second electrodes34B. The seven electrostatic sensing elements 12 are substantiallyparallel to each other. The distance between two adjacent electrostaticsensing elements 12 is about 3 mm. Each of the electrostatic sensingelements 12 comprises a single walled carbon nanotube or few-walledcarbon nanotube. The single walled carbon nanotube or few-walled carbonnanotube has a diameter of about 3 nm, and a length of about 10 mm.

The electrometer 300 includes N electrostatic sensing elements 12 inseries which can increase the sensing area and sensitive. Theelectrometer 300 is more suitable when the measured object has a certainarea and low static electricity potential.

Referring to FIG. 6 and FIG. 7, an electrostatic distribution measuringinstrument 400 of one embodiment includes a sensing module 40 and acontrol module 70 electrically connected to the sensing module 40.

The sensing module 40 includes a plurality of electrostatic sensingelements 12. The number of the sensing elements 12 is N, where N is aninteger greater than 1. The N electrostatic sensing elements 12 arespaced apart from each other. Each of the N electrostatic sensingelements 12 includes two opposite ends. Each end of the N electrostaticsensing elements 12 is connected to the control module 70.

The control module 70 includes a measuring unit 72 and a processing unit54. The measuring unit 72 is electrically connected to the Nelectrostatic sensing elements 12. The measuring unit 72 is used tomeasure the resistance variation ΔR of each of the N electrostaticsensing elements 12 and transmit the resistance variation ΔR to theprocessing unit 54. The measuring unit 72 may measure each of the Nresistance variation ΔR simultaneously, or measure each of the Nresistance variation ΔR sequentially. It is understood that the controlmodule 70 can also be replaced by N control module 50.

The electrostatic distribution measuring instrument 400 in theembodiment shown in FIG. 7 is similar to the electrometer 100 in theembodiment shown in FIG. 1, except that the electrostatic distributionmeasuring instrument 400 includes N electrostatic sensing elements 12.The control module 70 is electrically connected to the N electrostaticsensing elements 12 and measures the resistance variation ΔR of each ofthe N electrostatic sensing elements 12. The N electrostatic sensingelements 12 are insulated from each other. The arrangement of the Nelectrostatic sensing elements 12 is not limited. In one embodiment, theN electrostatic sensing elements 12 are substantially parallel to eachother. The distance between two adjacent electrostatic sensing elements12 can be in a range from about 2 mm to about 2 cm.

In one embodiment, the sensing module 40 includes seven electrostaticsensing elements 12. The seven electrostatic sensing elements 12 aresubstantially parallel to each other. The distance between two adjacentelectrostatic sensing elements 12 is about 3 mm. Each of theelectrostatic sensing elements 12 comprises a single walled carbonnanotube or few-walled carbon nanotube. The single walled carbonnanotube or few-walled carbon nanotube has a diameter of about 3 nm, anda length of about 10 mm.

The electrostatic distribution measuring instrument 400 includes Nelectrostatic sensing elements 12 connected to the control module 70respectively. The electrostatic distribution measuring instrument 400can measure a electrostatic distribution of the measured object,especially when the measured object has a certain shape.

The embodiments shown and described above are only examples. Even thoughnumerous characteristics and advantages of the present technology havebeen set forth in the foregoing description, together with details ofthe structure and function of the present disclosure, the disclosure isillustrative only, and changes may be made in the detail, including inmatters of shape, size and arrangement of the parts within theprinciples of the present disclosure up to, and including, the fullextent established by the broad general meaning of the terms used in theclaims.

Additionally, it is also to be understood that the above description andthe claims drawn to a method may include some indication in reference tocertain steps. However, the indication used is only to be viewed foridentification purposes and not as a suggestion as to an order for thesteps.

What is claimed is:
 1. An electrometer comprising: a sensing modulecomprising a plurality of electrostatic sensing elements spaced fromeach other, and a plurality of second electrodes, wherein the pluralityof electrostatic sensing elements and the plurality of second electrodesare alternately arranged in a series connection comprising two ends; andeach of the plurality of electrostatic sensing elements is single walledcarbon nanotube or few-walled carbon nanotube; and a control modulecoupled to the two ends, wherein the control module is configured tomeasure a resistance variation ΔR of the series connection and convertthe resistance variation ΔR into a static electricity potential.
 2. Theelectrometer of claim 1, wherein the plurality of electrostatic sensingelements are substantially parallel to each other.
 3. The electrometerof claim 2, wherein a distance between two adjacent electrostaticsensing elements of the plurality of electrostatic sensing elements isin a range from about 2 mm to about 2 cm.
 4. The electrometer of claim3, wherein the distance is about 3 mm.
 5. The electrometer of claim 1,further comprising an insulating substrate, wherein the seriesconnection is located on a surface of the insulating substrate.
 6. Theelectrometer of claim 5, wherein the insulating substrate comprisesflexible material.
 7. The electrometer of claim 6, wherein the flexiblematerial is plastic or resin.
 8. The electrometer of claim 1, furthercomprising two first electrodes located on the two ends of the seriesconnection, and the control module is coupled to the series connectionvia the two first electrodes.
 9. The electrometer of claim 1, whereinthe control module comprises a measuring unit and a processing unit; andthe measuring unit is coupled to the two ends of the series connection,the measuring unit is configured to measure the resistance variation ΔRof the series connection and transmit the resistance variation ΔR to theprocessing unit, and the processing unit is configured to convert theresistance variation ΔR into the static electricity potential.
 10. Theelectrometer of claim 1, wherein the few-walled carbon nanotube is acarbon nanotube with wall from two layers to six layers.
 11. Theelectrometer of claim 1, wherein a diameter of each of the plurality ofelectrostatic sensing elements is less than or equal to 5 nm.
 12. Theelectrometer of claim 1, wherein a length of each of the plurality ofelectrostatic sensing elements is less than or equal to 5 mm.
 13. Theelectrometer of claim 1, further comprising an alarm unit whichmonitoring the static electricity potential; and when the staticelectricity potential reaches a preset threshold, the alarm unit sendsout alarm signals.
 14. An electrometer comprising: a sensing modulecomprising a plurality of electrostatic sensing elements spaced fromeach other and a plurality of second electrodes, the number of theplurality of electrostatic sensing elements is N and the number of theplurality of second electrodes is N−1, N is an integer greater than 1,wherein the plurality of electrostatic sensing elements and theplurality of second electrodes are alternately arranged in a seriesconnection comprising two ends, and each of the plurality ofelectrostatic sensing elements is single walled carbon nanotube orfew-walled carbon nanotube; and a control module coupled to the twoends, wherein the control module is configured to measure a resistancevariation ΔR of the series connection and convert the resistancevariation ΔR into a static electricity potential.
 15. The electrometerof claim 14, wherein the plurality of electrostatic sensing elements aresubstantially parallel to each other.
 16. The electrometer of claim 15,wherein a distance between two adjacent electrostatic sensing elementsof the plurality of electrostatic sensing elements is in a range fromabout 2 mm to about 2 cm.
 17. The electrometer of claim 14, furthercomprising two first electrodes located on the two ends, the controlmodule is coupled to the series connection via the two first electrodes.18. The electrometer of claim 14, wherein the few-walled carbon nanotubeis a carbon nanotube with wall from two layers to six layers.
 19. Theelectrometer of claim 14, wherein a diameter of each of the plurality ofelectrostatic sensing elements is less than or equal to 5 nm.
 20. Theelectrometer of claim 14, wherein a length of each of the plurality ofelectrostatic sensing elements is less than or equal to 5 mm.